Thomas Tuchel has caused a defensive "mess" at Paris Saint-Germain by using Marquinhos in midfield, according to ex-striker Mevlut Erding.
Brazil international Marquinhos has been deployed in midfield in recent games by PSG head coach Tuchel.
The German has instead used midfielder Danilo Pereira, signed on loan from Porto, at the back.
Erding, who made 109 appearances for PSG between 2009 and 2012, claimed Tuchel has made a tactical blunder with his use of the PSG skipper.
"Marquinhos must be the leader of this team, but in defence. This is where he is the leader," Erding told L'Equipe.
"It's a mess! In midfield, he loses his influence. I do not understand this choice of Thomas Tuchel. He could justify it before to troubleshoot, to tinker, when there was no Danilo Pereira.
"Marquinhos will have the leadership of this team but in central defence. It is he who embodies the succession of Thiago Silva in all areas."
PSG claimed a 2-0 victory over Istanbul Basaksehir on Wednesday to register their first win in the Champions League this season thanks to two goals from Everton loanee Moise Kean.
They are top of Ligue 1 on goal difference ahead of second-placed Lille, who also have 18 points.